1. Field of the Invention
The present invention relates to a disc changer. Particularly, the invention relates to a disc changer incorporated in a disc drive unit, the disc changer having a protector that prevents a failure, in moving a disc, attributable to a displacement of a mechanical part of the disc drive unit when an external oscillation is applied to the mechanical part at the time of moving the disc.
2. Description of the Related Art
Conventionally, a cassette tape has been the mainstream medium recorded with music to provide music in a motor vehicle. However, a disc medium (hereinafter simply referred to as a disc) such as a compact disc (CD) and a mini disc (MD) is now mainly used in place of the cassette tape. Because the disc is thinner than the cassette tape, and particularly because an optical disc is not in a case, the accommodation space can be small. Therefore, a disc changer that accommodates plural discs in a reproducing unit and reproduces the recorded content by changing the discs is popular. A disc changer is also being developed for a digital versatile disc (DVD) type of optical disc.
This disc changer of optical discs has a disc accommodation rack capable of separately accommodating plural discs, one by one, inside a casing. A swing arm takes out a desired one of the discs from this disc accommodation rack, and reproduces the content of the disc using an optical head. When the reproduction ends, the swing arm returns the disc to the disc accommodation rack. In general, a turntable on which a disc is rotated and a clamper that fixes the disc onto the turntable are provided at the front end of the swing arm. An optical head moves in a radial direction of the optical disk, on a moving path formed on the swing arm, on the disc that rotates on the turntable, thereby reproducing the information recorded on the disc. Generally, the disc changer has the disc accommodation rack movably arranged, in the up and down directions, to facilitate the taking out of a desired one disc from the disc accommodation rack.
An early CD disc changer was large in size, and was accommodated in a trunk of a motor vehicle. However, due to an increasingly compact size of the disc changer in recent years, the disc drive unit that incorporates the disc changer can be accommodated in a center console of an instrument panel of the motor vehicle.
However, as a result of the small disc changer in the disc drive unit, the disc changer has a risk of suffering an operating failure. This is because, in the miniaturized disc changer, parts within the disc changer have smaller margins in size. Therefore, when an external oscillation is applied to the disc drive unit during the change of discs or during the taking in and out of a disc into and from the disc accommodation rack within the disc drive unit, the disc comes into contact with parts of the disc changer, or an operation failure occurs, at the swing arm, in clamping a disc onto the turntable.
In order to prevent the malfunction of the disc changer due to the application of an oscillation, it is considered suitable to arrange that an oscillation sensor such as an acceleration sensor detects a size of the oscillation applied to the disc drive unit and, when an oscillation is detected, the disc drive unit stops the operation of changing discs or clamping a disc. However, the addition of the oscillation sensor to the disc drive unit results in an increase in the cost of the disc drive unit.